1. Field of the Invention
The present invention relates to an imaging optical device such as TV camera, electronic camera, video camera or industrial imaging instrument, and more particularly to an imaging optical device having anti-vibration and tracking functions.
2. Related Background Art
For an imaging optical device having anti-vibration and tracking functions, a servo type anti-vibration device for a TV camera and an image tracking device as disclosed in Japanese Patent Publication No. 25509/1984 have been proposed. The former device absorbs and relieves vibration of the device due to vibration of a vehicle by mechanically dumping the vibration by an air dumper. This device measures absolute angular acceleration, absolute angular velocity and absolute angle in a tilt space applied to a camera lens system by a pair of acceleration meters, rute gyrometers, or free gyrometers to detect the absolute position of the camera. This information is fed back to a motor which controls an entire TV camera so that the attitude of the entire TV camera is controlled to prevent vibration.
In the latter anti-vibration device, a tracking target is imaged by a TV camera. Images having a time difference are stored in a scan conversion memory, center positions of tracking targets of the stored images are detected, and a body of the TV camera is driven through a universal head by a control signal. This signal is derived from the difference between the center positions of the tracking targets.
Since this device drives the entire TV camera, it requires a large size high power actuator. Thus, the device is of large size and requires a large amount of power.
In "Anti-Vibration Device For a TV Camera Mounted on a Moving Vehicle" NHK Technical Laboratory Monthly Report, Vol. 117, No. 4 (April, 1974), a known liquid prism such as that disclosed in Japanese Patent Publication No. 11906/1966, that is a prism including a pair of parallel glass plates which can be tilted to each other and a rubber bellows to define a space in which liquid is filled is provided. Angles of vertical and horizontal movement of a TV camera by vibration are detected by vertical and horizontal pairs of gyrometers, and the angle of the parallel glass plates is changed by a gyromoment to form a prism apex angle necessary to compensate vibration of image. Since this device has transmission mechanisms among devices such as gyrometers, gyromoment and liquid prism, the device is of large size and heavy. Further, since it utilizes an inertia of the gyrometer, it is difficult to smoothly pan the device.
In another prior art anti-vibration device, an imaging optical system is arranged in a lens barrel and an image picked up by an imaging optical system is taken out by an imaging sensor as an image signal, which is processed to detect vibration of the image, distance of movement and direction of movement. A motor which presents vibration of the image by the detected signals is arranged in a body of the camera. Thus, the lens barrel and the camera body are together driven by the anti-vibration means, as a result, the device is of large size and a high power drive motor is required.